The father and all eight offspring were diagnosed with TS. The mother and her family did not have the disorder. Two children and the father also had obsessive-compulsive disorder. The State lab took DNA samples from all family members, found the one region of the genome that all affected individuals shared, and then identified a rare mutation in HDC within this region, which resulted in the mutated protein losing its function.

State said past work on brain histamine by other labs shows that mice with low levels are more prone to repetitive behaviors that are similar to human tics, and that increasing brain histamine reverses this problem.

"The opportunity to go directly from a rare genetic finding to a trial of a new approach to treatment in a neuropsychiatric disorder is very unusual," said State. "We were lucky to happen across a gene pointing to a well-studied area in neuroscience. There are several new medications in development that increase the release of brain histamine. Based on this genetic finding, these compounds would be good candidates for new treatments for Tourette."

Source: Yale University